“There needs to be some emphasis placed on finding a structure that will make this economically viable because there are opportunities here for providers to grow their businesses substantially,” said Beth Almeida, executive di-rector of the Washington-based National Institute on Retirement Security.

The administration may want to consider combining various employers’ auto IRAs into larger pools of assets — much like the concept behind multiemployer defined benefit plans, she suggested.

With these plans, which are most typically utilized by union workers, a number of smaller companies contribute to the one single fund that’s managed by an outside board of trustees.

By pooling the auto-IRA assets, mutual fund companies, financial advisers, record keepers and administrators could take advantage of the “tremendous economies of scale that 75 million people could provide,” Ms. Almeida said.